Pagewidth inkjet printhead assembly with longitudinally extending sets of nozzles

Abstract

A pagewidth inkjet printhead assembly includes an elongate substrate that defines a plurality of ink inlet channels. A drive and control circuitry layer is positioned on the substrate. A plurality of nozzle chamber structures is arranged on the substrate to define a number of longitudinally extending sets of nozzle chamber structures. Each set has a series of adjacent pairs of nozzle chamber structures. Each nozzle chamber structure defines a nozzle chamber in fluid communication with a respective ink inlet channel and an ink ejection port in fluid communication with the nozzle chamber. A plurality of elongate micro-electromechanical actuators is fast at one end to the substrate to receive electrical drive signals from the drive and control circuitry layer. A plurality of ink ejecting members is positioned in respective nozzle chambers. Each ink ejecting member is fast with a respective opposite end of each micro-electromechanical actuators to be displaced relative to the substrate on receipt of a drive signal by the associated actuator, thereby ejecting ink from the ink ejection port.

1. A pagewidth inkjet printhead assembly which comprises:
 an elongate substrate that defines a plurality of ink inlet channels; 
 a drive and control circuitry layer positioned on the substrate; 
 a plurality of nozzle chamber structures arranged on the substrate to define a number of longitudinally extending sets of nozzle chamber structures, each set having a series of adjacent pairs of nozzle chamber structures, each nozzle chamber structure defining a nozzle chamber in fluid communication with a respective ink inlet channel and an ink ejection port in fluid communication with the nozzle chamber; 
 a plurality of elongate micro-electromechanical actuators fast at one end to the substrate to receive electrical drive signals from the drive and control circuitry layer; and 
 a plurality of ink ejecting members positioned in respective nozzle chambers and fast with respective opposite ends of the micro-electromechanical actuators to be displaced relative to the substrate on receipt of a drive signal by the associated actuator, thereby ejecting ink from the ink ejection port; 
 wherein the nozzle chamber structures and the associated micro-electromechanical actuators are configured so that a region between sets contains consecutively overlapping actuators. 
 
   
   
     2. A pagewidth inkjet printhead assembly as claimed in  claim 1 , in which the drive and control circuitry includes a plurality of control logic and associated power transistor circuits interposed between respective actuators and the substrate. 
   
   
     3. A pagewidth inkjet printhead assembly as claimed in  claim 2 , in which each actuator includes a heating element connected to the associated circuit and a body of material capable of thermal expansion to perform work, the heating element being fast with the body and interposed between the body and the substrate such that heating of the body by the heating element on receipt of an electrical signal from the associated circuit results in displacement of the actuator. 
   
   
     4. A pagewidth printhead assembly as claimed in  claim 3 ,in which each control logic and power transistor circuit includes a plurality of substantially parallel traces that extend transversely with respect to the actuator, each heating element defining a series of corrugations that correspond generally with the traces. 
   
   
     5. A pagewidth printhead assembly as claimed in  claim 3 ,in which each heater element includes a pair of heater arms that are formed on either side of a tapered slot so that they are narrower toward a fixed end of the actuator,giving increased resistance and therefore heating and expansion in that region. 
   
   
     6. A pagewidth printhead assembly as claimed in  claim 3 ,in which the heater element and the ink ejecting member incorporate a common metal layer that defines a discontinuity to isolate the ink ejecting member from the heater element.